Dustin Oedekoven said Wednesday the owner of the 21-month-old female elk noticed the animal was sick and contacted his veterinarian. The USDA’s National Veterinary Services Laboratory in Ames, Iowa, later confirmed samples tested positive for the disease.

Chronic wasting disease is endemic in free-ranging deer and elk in and around the Black Hills. The disease was last diagnosed in captive elk in South Dakota in 2001.

CWD is a fatal disease that strikes the nervous system in deer, elk and moose. Oedekoven says state and federal animal health officials are working with the owner of the affected herd to investigate the disease and mitigate further infection.